he meant thats a lot of oil per parts of gas.
i run 32:1. yamalube. never a problem. I've even ran 40:1 before without a problem. Just feel safer at 32:1
Drain your fluid. Take off the clutch cover. See that little nut and screw head in the middle of the clutch basket. Get out your 8mm and loosen it. With your hand move the little lever where your clutch cable connects near the crank case all the way forward. Now tighten the screw in the center of the basket untill the little notch on the tip of the lever lines up with the (protuberance) on the crank case. Tighten your 8mm lock washer back and make sure you adjust the slack out of the clutch cable up near your handlebars again.
I think that would mean you have a 65.25mm size piston in there. which means you can get that cylinder bored some more still. no need for a sleeve yet. But to be sure bring it to a shop and ask them. You should be able to get everything done for around $350.
Why go from 18cc to 19cc? That's gonna lower the compression. Unless you want to run pump gas then your gonna need at least 20cc domes. I'd stay where your at.
4mm stroker doesn't need any case mods.
If your tuned in good you should pull on that 450r. Just race em and tell us.
From my calculations I figure about 200rwhp. Engine 50hp, 150 stickers at about 1hp a piece. for that much you'd think he'd clean the bike and replace the bent ass front bumper. What a loser.